T1557
Adversary-in-the-Middle
Linux · macOS · Network Devices · Windows4 pieces on this siteT1557 on attack.mitre.org
Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as Network Sniffing, Transmitted Data Manipulation, or replay attacks (Exploitation for Credential Access). By abusing features of common networking protocols that can determine the flow of network traffic (e.g.
If this is happening now
Checklists and playbooks to open while the alert is still live.
Cloud account takeover response plan: sessions, methods, devices and grants, then what they read
A successful sign-in the user did not make, in Microsoft Entra ID and Microsoft 365. A password reset alone evicts almost nobody. The plan works through the order that does, how to tell a guessed password from a stolen session, and how to answer what they read.
First 15 minutes: a successful sign-in from an IP address nobody recognises
A user's account signed in successfully from an address, country or device that does not fit. How to tell a traveller from a stolen session in five minutes, and what to cut off if it is the second.
First 15 minutes: a user typed their password into a phishing page
Assume the session was taken, not just the password. Revoke first, find everybody else the email reached, and check what the attacker did with the time they had.
Your DNS records changed and nobody here did it
Mail stops arriving, a site resolves somewhere unexpected, a certificate appears that nobody requested, or the registrar emails about a change nobody made.
how MITRE says to see it
Detect Adversary-in-the-Middle via Network and Configuration Anomalies
- Detects suspicious DNS/ARP poisoning attempts, unauthorized modifications to registry/network configuration, or abnormal TLS downgrade activity. Correlates changes in system configuration with subsequent unusual network flows or authentication events.
- Detects unauthorized edits to /etc/hosts, /etc/resolv.conf, or suspicious ARP broadcasts. Correlates file modifications with subsequent unexpected network sessions or service creation.
- Detects unauthorized edits to system configuration profiles, unexpected certificate trust changes, or abnormal ARP/DNS patterns indicative of interception.
- Detects unauthorized firmware or configuration changes enabling adversary-in-the-middle positioning (e.g., route injection, DNS spoofing, SSL downgrade). Behavioral analytics focus on sudden changes to routing tables or image file integrity failures.
what reduces it
- M1031 Network Intrusion Prevention. Network intrusion detection and prevention systems that can identify traffic patterns indicative of AiTM activity can be used to mitigate activity at the network level.
- M1035 Limit Access to Resource Over Network. Limit access to network infrastructure and resources that can be used to reshape traffic or otherwise produce AiTM conditions.
- M1037 Filter Network Traffic. Use network appliances and host-based security software to block network traffic that is not necessary within the environment, such as legacy protocols that may be leveraged for AiTM conditions.
- M1017 User Training. Train users to be suspicious about certificate errors. Adversaries may use their own certificates in an attempt to intercept HTTPS traffic. Certificate errors may arise when the application’s certificate does not match the one expected by the host.
- M1030 Network Segmentation. Network segmentation can be used to isolate infrastructure components that do not require broad network access. This may mitigate, or at least alleviate, the scope of AiTM activity.
- M1042 Disable or Remove Feature or Program. Disable legacy network protocols that may be used to intercept network traffic if applicable, especially those that are not needed within an environment.